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<head>
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    <title>Document</title>
    <style>
        div {
            width: 200px;
            height: 200px;
            background-color: pink;
        }
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</head>

<body>
    <div></div>
    <script>
        $(function () {
            console.log($('div').css('width'));

            // $('div').css('width', '300px')
            // $('div').css('width', 300)
            // $('div').css(width, '300px')  属性名必须加引号

            $('div').css({
                width: 400,
                height: 500,
                backgroundColor: "red"
                // 如果是复合属性则必须采取驼峰命名法，如果值不是数字，则需要加引号
            })
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